Next Winter Could Be Unusually Frigid

New and bold data has been uncovered, suggesting that the winter of 2013-2014 may be unusually frigid ('frigid' being defined as temperatures ending up below normal for the winter timeframe).

The data I uncovered was the result of digging through records of the Arctic Oscillation. I put together the proposition of using early spring Arctic Oscillation values to predict the next winter's temperatures and atmospheric flow throughout the Northern Hemisphere. For this case, I used years where Arctic Oscillation values in February were negative, but the year after that, the AO values were even deeper into negative territory. For example, if February 1978 had an Arctic Oscillation value of -0.75, and February 1979 had a value of -2.08, I would use February 1978 to compare to the current year and see if the patterns match up. If the patterns do match up, it would be plausible to expect a negative Arctic Oscillation in the forthcoming winter, thus a higher potential for cold. The image above shows 500 millibar height anomalies for five different years- February 2009, 1984, 1977, 1968 and 1962. You may immediately notice years like 2009 for its Northeast impacts, as well as 1984, the year before the epic polar vortex collapse. All of these years have had a negative Arctic Oscillation value in February of that year, to be followed one year later by an even more negative AO value. A quick glance over the image reveals low pressure in the East US, general high pressure across Canada and towards Greenland, as well as to the north of Europe. Low pressure tendencies are found in Western Europe, the Bering Sea and East Asia. I'm going to show observed height anomalies for this past February next; bear in mind the placement of the high and low pressure tendencies in the image above when looking at February 2013 below.

Let's run over the checklist of high and low pressure tendencies we looked at above and compare them to what February 2013 held in store. We see low pressure in the East US, as well as high pressure anomalies in Canada and into Greenland. We also observe deep low pressure in western Europe, in addition to East Asia and the Bering Sea. High pressure prevails to the north of Eurasia. Taking a look at the images together should set off multiple alarms- all the items I listed in the last couple of sentences appeared not only in February 2013, but also in the averaged-out 5 years image at the top of this post. Now, there are a few differences, like extreme high pressure in the northeast Pacific in 2013, as well as more extended low pressure in the multiple year image that we don't see in 2013. However, you get the general idea- there are several similarities between these images.

So, what does this all mean? Well, we've managed to figure out that the atmospheric flow in February 2013 is at least reasonably similar to that of the five years listed above. This means that, going forward, it is plausible to be on the lookout for a pattern similar to 2009, 1984, 1977, 1968 and 1962 going forward. What this also means is that the winter of 2013-2014 could see some similar features as far as the winters of 2009-2010, 1984-1985, 1977-1978, 1968-1969, and 1962-1963 go.

The image above shows average surface temperature anomalies for the aforementioned winters. We see a wide swath of below normal temperatures stretching from the northern Plains into the Midwest and engulfing the Central and East US regions. This widespread cold shouldn't be surprising- January 1985 was the month where the polar vortex truly collapsed, while the winter of 2009-2010 was the snowiest of record for many. All in all, the analog years spell a chilly winter ahead.

I understand if you don't really get how I chose the analog years, my explanation at the top may not have been as sufficient as I would have liked. If you have any questions, comment them below and I'll try to answer them as soon as possible.

**Don't forget, the Anniversary Festivities begin April 26th with two MAJOR posts!!**

Andrew

Spring Makes a Big Comeback

It looks like spring is going to make a huge comeback in the next week, as model guidance is building consistency with very warm temperatures encompassing everyone in the Plains and east.

Model forecasts of medium-range mid-level height anomalies show a massive ridge building over North America in the next 6-10 days. The European model (left) has this ridge centered in southeast Canada, bringing unusually warm temperatures to those in the East and Central US. The American GFS model on the left portrays this ridge of high pressure splitting into two areas of interest- the West US and Canadian Maritimes. The two model solutions are extremely different with the atmospheric set-up, but predicted temperature spreads are really pretty similar between the two forecast systems.

This nine-panel image of predicted maximum temperatures over the dates listed below each image show how this massive warm-up is projected to evolve. The warmest temperatures seem to want to go over the entire nation, save the Rocky Mountains. The strength of the ridge shown above would certainly support such an idea of widespread warmth, so my position on the idea of this extreme spread of warmth is not one of rejection.

Andrew

Notice

I figured this should probably be addressed before anyone begins to wonder and rumors swirl.

Posting has been much more limited as of late due to a multitude of factors, the most prevalent being the lack of topics to post about. Also factoring into the quiet trend here is how the last few weeks have become unusually busy, restricting my access to the computer. Until we get back into a severe weather event and those dreadful summer heat waves, posting may very well remain below normal. I have no timetable for when this busy period will end, unfortunately.

Andrew

Spring Pulls A Vanishing Act; Returns for May

Spring continues to do its magic and will be pulling a vanishing act until the beginning of May.

Pictured above is the 500 millibar height anomalies from forecast Day 6 to Day 10. Cold colors show low pressure anomalies, while warm colors portray high pressure. In the forecast image above, we see strong low pressure building over the Arctic to allow for a strengthening polar vortex. As a result of this  strengthening, warm weather is typically favored. However, high pressure building south of Greenland and in the Northeast Pacific will coerce the low pressure further south and allow cold air to make itself available in all the areas shown in blue. Again, usually, warm air would be favored as the cold air would be kept up north in the presence of such strong low pressure over the Arctic. However, the angling of those two previously mentioned high pressure systems will let the polar vortex squeeze some of that unseasonably colder air further south.

The long range American ensembles show 500 millibar height anomalies over the next sixteen days from left to right, top to bottom. We can see the polar vortex pushing south towards the US/Canada border, but by the time May rolls around in the bottom row of forecast images, we see abundant high pressure across the nation. This abundant high pressure formation is what is supposed to happen with strong low pressure in the Arctic. It looks like the nation-wide high pressure formation in early May would be tempered in the East US just because of persistent high pressure stirring around Greenland, but cold air should not prevail like it will in the next couple of days.

Andrew

Snow Rounds Out Atypical April

It looks like snow will be rounding out the last days of April.

The NAM model forecast has two swaths of accumulating snow in the Midwest and Plains. The stripe of snow in the Midwest looks to put down upwards of 6 inches in many spots, especially across Wisconsin and southeast Minnesota. Lighter totals will be observed into northern Nebraska and southern South Dakota. The second body of snow will be more significant, but will cover less ground. Kansas will get hammered with totals flirting with (and in some cases, exceeding) one foot of snow. The heaviest amounts appear to be centered in the northern part of the state, with central Kansas being the cutoff for the heaviest snow. Normally, I would address this as Old Man Winter's last hurrah, but with the way this April has been going, I wouldn't be surprised to see sporadic, light snowfall chances into May.

Andrew